Tim -
Many years and several lifetimes ago, there was fairly feverish activity
amoung auto buffs to design and build home brewed electronic ignition
systems.
A major feature of, and frequent stumbling block in the design of, such
systems was the main DC to DC power supply. (There shall forever be a warm
place in my heart for the thousands of venerable 2N3055s that sacrificed
their lives to these projects!).
Many of the designs involved obtaining and salvaging the windings off of a
old TV power supply transformer from a discarded, tube-type TV set. You
know, the kind that generated 350-500 VDC for the deflection oscillators,
various other anode and screen voltages for the many tubes in the set, and
finally, 2 or 3 filiment supplies.
The salavged magnet wire was then used to wind the inverter transformer on a
particular "tape-wound" torrid.
The push-pull power transistors were switched alternately by a pair of small
windings on the torrid.
The result was a high frequency square-wave that was rectified to charge a
capacitor which was dumped into the ignition coil in the usual manner.
In those days(the 50's and 60's), HeathKit sold a kit version of this basic
circuit. I built two of these over the years, one for my rather "cranky"
and tempermental 1960 Chevy powered by the brute force Duntov 348 c.i.d.
wedge head V-8. The other went into a 1970 Super-Bug which would start
reliably down to 20 below in Minneapolis, MN, with the aid of the Heath
ignition.
The point of all this nostalgia is to suggest that a creative google search
might produce a hit or two on one of these old projects. Or, perhaps, one
of us old farts on the list may still have access to a manual for the
HeathKit or project notes for one of the pure home-brew types.
Such a torrid power supply could easily be adapted to your required output
voltage by playing with the secondary windings.
Best wishes, Bob Smith
--- Avoid computer viruses, Practice safe hex ---
-- Specializing in small, cost effective
embedded control systems --
http://www.smithmachineworks.com/embedprod.html
Robert L. (Bob) Smith
Smith Machine Works, Inc.
9900 Lumlay Road
Richmond, VA 23236 804/745-1065
[EMAIL PROTECTED]
----- Original Message -----
To: "Multiple recipients of list CHIPDIR-L" <[EMAIL PROTECTED]>
Sent: Thursday, December 18, 2003 1:54 PM
> Hello Group,
> Does anybody have info or links to sites on high power D.C./D.C. supplies.
> I believe they are push/pull bridge type popular with auto stereo power
> amplifiers.
> They use enameled 18,16 ga. wire and a torroid with a typical step-up,
> center tapped secondary, and a center tapped primary connected to the
> battery with two banks of FET's switched to ground at 30 or 40 khz in bi
> phase.
> Any one familiar?
> I know the technical details for winding a torroid are extensive to say
the
> least but I was hoping there was familiar and had something basic from a
> working circuit available.
> I have a rail of old FET's and want to wind a big transformer for
something
> POWERFUL... if you know what I mean.
> In the words of Tim Allen. POWER... Aarrrrg...
> And sorry for the long note.
>
> Thanks
>
> Jim
>
> >From: "Brad O'Dell" <[EMAIL PROTECTED]>
> >Reply-To: [EMAIL PROTECTED]
> >To: Multiple recipients of list CHIPDIR-L <[EMAIL PROTECTED]>
> >Subject: HUF76121D3S MOSFET replacement
> >Date: Mon, 15 Dec 2003 05:44:19 -0800
> >
> >Hello everybody,
> >I was repairing a socket 370 motherboard and needed to replace a
noticeably
> >damaged Harris HUF76121D3S (part is branded 76121D, also Fairchild has
this
> >part). All I have easy access to is a RFP30N06LE. Will this be a
suitable
> >replacement besides the package style (TO-252AA versus TO-220AB)?
> >
> >starter data:
> >both are N-channel enhancement mode logic level MOSFETs
> >replacement has higher voltage rating (Vdss and Vdgr 60V vs. 30V)
> >replacement has higher current rating (Id 30A vs. 20A)
> >replacement seems to be faster
> >however, drain-to-source ON resistance is more with replacement (Rds(ON)
> >max. .047ohm vs. .030ohm). Would this significantly affect circuit
> >operation? Also the HUF76121 Rds(on) was rated for the part maximum
> >current of 20A, whereas the RFP30N06 Rds(on) was rated for that part's
> >maximum current of 30A. How would I recalculate the RFP device's Rds(on)
> >with the lower current of 20A that will be used?
> >
> >Thanks,
> >Brad
>
> _________________________________________________________________
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> --
> Author: Tim Johnson
> INET: [EMAIL PROTECTED]
>
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--
Author: Robert Smith
INET: [EMAIL PROTECTED]
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